Assume that a completed well requires servicing. The typical servicing routine is to place a wireline in the tubing string with suitable remedial tools affixed to the wireline. Typically, the wireline is run through the wellhead equipment at a lubricator or stuffing box, all for the purpose of holding back the pressure and to thereby enable the wireline and associated tool to be lowered into the tubing string. There is a calculated risk in the use of a lubricator or stuffing box, and it is possible for pressure surges flowing up the tubing string to blow the remedial tool and wireline back toward or through the wellhead equipment. This is dangerous to the personnel and equipment. When the tools are forced upwardly, they may overrun the wireline and get tangled in it. This leads to snarled wireline and difficult fishing jobs.
The present apparatus is a type of catch mechanism adapted to be incorporated with a fishing tool. The particular remedial tool is not particularly important, and this apparatus can be used with many types of wireline operated remedial tools such as a bottom hole pressure recorder. As an example, tools which are typically manipulated from a wireline can be installed with the present invention. Such an installation as contemplated by this disclosure involves a conventional wireline which is extended into a tubing string, terminating at a rope socket having a conventional neck thereon. The present apparatus is located just below the finishing neck and is typically above the remedial tool. This enables this apparatus to be positioned close to the remedial tool so that any pressure surge encountered flowing upwardly through the tubing string will catch this apparatus and move it upwardly. It moves only slightly; the slight move is associated with setting the present apparatus so that further movement is prevented. That is, this apparatus includes tapered slips which ride on the exterior of a tapered cone, and the slips expand radially outwardly to lock against the surrounding tubing. There is some space between the tool and the tubing to enable some blow by, thereby reducing flow volume and constricting the flow upwardly through the tubing string. In effect, the apparatus prevents remedial tools from being blown up through the tubing string into the Christmas tree. Moreover, controlled flow permits the pressure flow from below the tool to set the tool and the controlled flow can be more readily handled by the equipment located at the wellhead. The controlled rate of flow pass this apparatus typically constricts but does not fully plug the tubing string, and is therefore desirable to prevent dangerous blowouts through the tubing string.
This apparatus is particularly described as a tethered tool run in tubing having a rope socket and conventional fishing neck on the top end. They are integrally joined with a cone therebelow, the cone cooperating with serrated slips which set and hold the tool when actuated. This tool is particularly helpful in supporting a cooperative remedial tool therebelow. The device is particularly advantageous in that an upward pull on the wireline unsets the device. The device is set by upward fluid flow. So long as the device supports substantial weight on the wireline, it can travel down the tubing string in an unset condition. An upward pull, whether the tool is moving upwardly or downwardly, maintains the device in a released condition. Therefore this does not interfere with running the tool into a tubing string. Moreover, it is supported on a wireline along with a number of weights. The number of weights can be changed to accommodate the size, weight and length of the remedial tool supported therebelow. Spring tension setting can be varied to also adjust the tool.
One important use of the tool is to prevent loss if the wireline breaks. The tool will set and snag a collar if the wireline breaks; the tool will not fall to the bottom of the tubing.
With the foregoing in view, this apparatus is summarized as a tool adapted to be run on a wireline which chokes but does not totally restrict a blowout from downhole. The tool is comprised of a rope socket having a conventional fishing neck and an integrally attached tapered cone therebelow. It supports in a spring arrangement, a telescoped stem and sliding sleeve thereabout. The sleeve is adapted to be connected to the fishing tool with suitable weight bars therebetween to adjust the position of the slips and tapered cone.